Default [Q] Point Cloud from HTC One M8

Does anyone know how to build a 3D point cloud with data from the dual cameras on a HTC One M8? In my program, I call DimensionPlusUtility.exportGeometryFromFile() to get a Geometry object. I can then call getVertices() on the Geometry object to get a float array containing apparently (x, y, z, w) tuples. What are the units of x, y, and z? x and y are in [-1, 1], and z is in [0, 1]. The dynamic range of z-values seems small for my images (usually between 0.85 and 1). Is there a way to convert these values to metric units? Has anyone had to calibrate the stereo pair?